Balanced mutual capacitance systems and methods

ABSTRACT

In some examples, a touch screen can include touch electrodes that can function as drive (Tx) electrodes and sense (Rx) electrodes during a touch sensing operation of the electronic device. The drive electrodes can include +Tx electrodes and -Tx electrodes that can receive drive signals that can have the same amplitude and frequency and opposite phases, for example. In some examples, the surface areas of the +Tx electrodes and the -Tx electrodes can be the same and the distances of the +Tx electrodes and -Tx electrodes from the Rx electrodes can be different. In some examples, the total charge coupled to a proximate or touching object can be zero, which can mitigate problems associated with ungrounded or poorly grounded objects in contact with the touch screen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.16/998,456, filed Aug. 20, 2020, the content of which is incorporatedherein by reference in its entirety for all purposes.

FIELD OF THE DISCLOSURE

This relates generally to capacitive touch sensors and, morespecifically, to mutual capacitance touch sensing techniques thatinclude balanced drive signals.

BACKGROUND OF THE DISCLOSURE

Many types of input devices are presently available for performingoperations in a computing system, such as buttons or keys, mice,trackballs, joysticks, touch sensor panels, touch screens and the like.Touch screens, in particular, are popular because of their ease andversatility of operation as well as their declining price. Touch screenscan include a touch sensor panel, which can be a clear panel with atouch-sensitive surface, and a display device such as a liquid crystaldisplay (LCD), light emitting diode (LED) display or organic lightemitting diode (OLED) display that can be positioned partially or fullybehind the panel so that the touch-sensitive surface can cover at leasta portion of the viewable area of the display device. Touch screens canallow a user to perform various functions by touching the touch sensorpanel using a finger, stylus or other object at a location oftendictated by a user interface (UI) being displayed by the display device.In general, touch screens can recognize a touch and the position of thetouch on the touch sensor panel, and the computing system can theninterpret the touch in accordance with the display appearing at the timeof the touch, and thereafter can perform one or more actions based onthe touch. In the case of some touch sensing systems, a physical touchon the display is not needed to detect a touch. For example, in somecapacitive-type touch sensing systems, fringing electrical fields usedto detect touch can extend beyond the surface of the display, andobjects approaching near the surface may be detected near the surfacewithout actually touching the surface.

Capacitive touch sensor panels can be formed by a matrix of transparent,semitransparent or non-transparent conductive plates made of materialssuch as Indium Tin Oxide (ITO). In some examples, the conductive platescan be formed from other materials including conductive polymers, metalmesh, graphene, nanowires (e.g., silver nanowires) or nanotubes (e.g.,carbon nanotubes). In some implementations, due in part to theirsubstantial transparency, some capacitive touch sensor panels can beoverlaid on a display to form a touch screen, as described above. Sometouch screens can be formed by at least partially integrating touchsensing circuitry into a display pixel stackup (i.e., the stackedmaterial layers forming the display pixels).

In some examples, a poorly grounded object touches or is proximate to atouch sensor panel. In some situations, the touch sensor panel may beunable to detect the poorly grounded object or the poorly groundedobject can cause errors in the touch data, such as a “negative pixeleffect” by coupling charge from the object to one or more senseelectrodes of the touch sensor panel. In some examples, poor groundingcan be mitigated using one or more algorithms applied to the sensedtouch data. In some examples, poor grounding can be mitigated throughthe design of the touch sensor panel and/or the touch scans performed atthe touch sensor panel.

BRIEF SUMMARY OF THE DISCLOSURE

Embodiments described herein relate generally to capacitive touchsensors and, more specifically, to mutual capacitance touch sensingtechniques that include balanced drive signals. In some examples, atouch screen can include a plurality of touch electrodes that canfunction as drive (Tx) electrodes and sense (Rx) electrodes during atouch sensing operation of the electronic device. The drive electrodescan include +Tx electrodes and -Tx electrodes that can receive drivesignals that can have the same amplitude and frequency and oppositephases, for example. In some examples, the surface areas of the +Txelectrodes and the -Tx electrodes can be the same and the distances ofthe +Tx electrodes and -Tx electrodes from the Rx electrodes can bedifferent. In some examples, the total charge coupled to a proximate ortouching object can be zero, which can mitigate problems associated withungrounded or poorly grounded objects in contact with the touch screen.In some examples, the net capacitive coupling of the +Tx electrodes and-Tx electrodes with the Rx electrodes can be non-zero, allowing touch tobe detected by detecting changes in the net mutual capacitances betweenthe +Tx electrodes and Rx electrodes and between the -Tx electrodes andRx electrodes.

A variety of arrangements of +Tx, -Tx, and Rx electrodes can be used,for example. In some examples, each respective touch node of the touchscreen can include an Rx electrode, a +Tx electrode, and a -Txelectrode. For example, each touch node can include one or more Rxelectrodes at least partially surrounded by one or more +Tx electrodes,which can be at least partially surrounded by one or more -Txelectrodes. In some examples, the touch screen can include rows andcolumns of drive and sense electrodes with touch nodes defined as theintersections of the rows and columns. For example, the Rx electrodescan be disposed in rows and the +Tx electrodes and -Tx electrodes can bedisposed in columns, wherein the +Tx electrodes can surround the -Txelectrodes. As another example, a touch sensor that includes one touchnode can include one or more +Tx electrodes located between one or moreRx electrodes and one or more -Tx electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1H illustrate example systems that can use balanced mutualcapacitance techniques according to examples of the disclosure.

FIG. 2 illustrates an example computing system including a touch screenthat can use balanced mutual capacitance techniques according toexamples of the disclosure.

FIG. 3A illustrates an exemplary touch sensor circuit corresponding to aself-capacitance measurement of a touch node electrode and sensingcircuit according to examples of the disclosure.

FIG. 3B illustrates an exemplary touch sensor circuit corresponding to amutual-capacitance drive line and sense line and sensing circuitaccording to examples of the disclosure.

FIG. 4A illustrates touch screen with touch electrodes arranged in rowsand columns according to examples of the disclosure.

FIG. 4B illustrates touch screen with touch node electrodes arranged ina pixelated touch node electrode configuration according to examples ofthe disclosure.

FIGS. 5A-5C illustrate exemplary circuit diagrams modeling mutualcapacitance touch sensing in various scenarios according to someexamples of the disclosure.

FIGS. 6A-6C illustrate exemplary electrode layouts of touch screensaccording to examples of the disclosure.

FIG. 7 illustrates a side view of an exemplary touch sensor according tosome examples of the disclosure.

FIGS. 8A-8B are flow charts illustrating exemplary processes includingbalanced mutual capacitance touch sensing according to some examples ofthe disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

In the following description of examples, reference is made to theaccompanying drawings which form a part hereof, and in which it is shownby way of illustration specific examples that can be practiced. It is tobe understood that other examples can be used and structural changes canbe made without departing from the scope of the disclosed examples.

Embodiments described herein relate generally to capacitive touchsensors and, more specifically, to mutual capacitance touch sensingtechniques that include balanced drive signals. In some examples, atouch screen can include a plurality of touch electrodes that canfunction as drive (Tx) electrodes and sense (Rx) electrodes during atouch sensing operation of the electronic device. The drive electrodescan include +Tx electrodes and -Tx electrodes that can receive drivesignals that can have the same amplitude and frequency and oppositephases, for example. In some examples, the surface areas of the +Txelectrodes and the -Tx electrodes can be the same and the distances ofthe +Tx electrodes and -Tx electrodes from the Rx electrodes can bedifferent. In some examples, the total charge coupled to a proximate ortouching object can be zero, which can mitigate problems associated withungrounded or poorly grounded objects in contact with the touch screen.In some examples, the net capacitive coupling of the +Tx electrodes and-Tx electrodes with the Rx electrodes can be non-zero, allowing touch tobe detected by detecting changes in the net mutual capacitances betweenthe +Tx electrodes and Rx electrodes and between the -Tx electrodes andRx electrodes.

A variety of arrangements of +Tx, -Tx, and Rx electrodes can be used,for example. In some examples, each respective touch node of the touchscreen can include an Rx electrode, a +Tx electrode, and a -Txelectrode. For example, each touch node can include one or more Rxelectrodes at least partially surrounded by one or more +Tx electrodes,which can be at least partially surrounded by one or more -Txelectrodes. In some examples, the touch screen can include rows andcolumns of drive and sense electrodes with touch nodes defined as theintersections of the rows and columns. For example, the Rx electrodescan be disposed in rows and the +Tx electrodes and -Tx electrodes can bedisposed in columns, wherein the +Tx electrodes can surround the -Txelectrodes. As another example, a touch sensor that includes one touchnode can include one or more +Tx electrodes located between one or moreRx electrodes and one or more -Tx electrodes.

FIGS. 1A-1H illustrate example systems that can use balanced mutualcapacitance techniques according to examples of the disclosure. FIG. 1Aillustrates an example mobile telephone 136 that includes a touch screen124 that can use balanced mutual capacitance techniques according toexamples of the disclosure. FIG. 1B illustrates an example digital mediaplayer 140 that includes a touch screen 126 that can use balanced mutualcapacitance techniques according to examples of the disclosure. FIG. 1Cillustrates an example personal computer 144 that includes a touchscreen 128 and a touch sensor panel 134 (e.g., a trackpad) that can usebalanced mutual capacitance techniques according to examples of thedisclosure. FIG. 1D illustrates an example tablet computing device 148that includes a touch screen 130 that can use balanced mutualcapacitance techniques according to examples of the disclosure. FIG. 1Eillustrates an example wearable device 150 that includes a touch screen132 and can be attached to a user using a strap 152 and that can usebalanced mutual capacitance techniques according to examples of thedisclosure. FIG. 1F illustrates an example remote control device 154that includes a touch sensor panel 138 that can use balanced mutualcapacitance techniques according to examples of the disclosure. FIG. 1Gillustrates an example earbud 156 that includes a touch sensor 160 thatcan use balanced mutual capacitance techniques according to examples ofthe disclosure. FIG. 1H illustrates an example stylus 158 that includesa touch sensor 162 that can use balanced mutual capacitance techniquesaccording to examples of the disclosure. It is understood that a touchscreen and balanced mutual capacitance techniques can be implemented inother devices, including future devices not yet in the marketplace.Additionally, it should be understood that although the disclosureherein primarily focuses on touch screens, the disclosure of balancedmutual capacitance techniques can be implemented for devices includingtouch sensor panels (and displays) that may not be implemented as atouch screen.

In some examples, touch screens 124, 126, 128, 130 and 132, touch sensorpanels 134 and 138 and touch sensors 160 and 162 can be based onself-capacitance. A self-capacitance based touch system can include amatrix of small, individual plates of conductive material or groups ofindividual plates of conductive material forming larger conductiveregions that can be referred to as touch electrodes or as touch nodeelectrodes (as described below with reference to FIG. 4B). For example,a touch screen can include a plurality of individual touch electrodes,each touch electrode identifying or representing a unique location(e.g., a touch node) on the touch screen at which touch or proximity isto be sensed, and each touch node electrode being electrically isolatedfrom the other touch node electrodes in the touch screen/panel. Such atouch screen can be referred to as a pixelated self-capacitance touchscreen, though it is understood that in some examples, the touch nodeelectrodes on the touch screen can be used to perform scans other thanself-capacitance scans on the touch screen (e.g., mutual capacitancescans). During operation, a touch node electrode can be stimulated withan alternating current (AC) waveform, and the self-capacitance to groundof the touch node electrode can be measured. As an object approaches thetouch node electrode, the self-capacitance to ground of the touch nodeelectrode can change (e.g., increase). This change in theself-capacitance of the touch node electrode can be detected andmeasured by the touch sensing system to determine the positions ofmultiple objects when they touch, or come in proximity to, the touchscreen. In some examples, the touch node electrodes of aself-capacitance based touch system can be formed from rows and columnsof conductive material, and changes in the self-capacitance to ground ofthe rows and columns can be detected, similar to above. In someexamples, a touch screen can support multi-touch, single touch,projection scan, etc., touch functionality.

In some examples, touch screens 124, 126, 128, 130 and 132, touch sensorpanels 134 and 138 and touch sensors 160 and 162 can be based on mutualcapacitance. A mutual capacitance based touch system can includeelectrodes arranged as drive and sense lines (e.g., as described belowwith reference to FIG. 4A) that may cross over each other on differentlayers (in a double-sided configuration) or may be adjacent to eachother on the same layer. The crossing or adjacent locations can formtouch nodes. During operation, the drive line can be stimulated with anAC waveform and the mutual capacitance of the touch node can bemeasured. As an object approaches the touch node, the mutual capacitanceof the touch node can change (e.g., decrease). This change in the mutualcapacitance of the touch node can be detected and measured by the touchsensing system to determine the positions of multiple objects when theytouch, or come in proximity to, the touch screen. As described herein,in some examples, a mutual capacitance based touch system can form touchnodes from a matrix of small, individual plates of conductive material.

In some examples, touch screens 124, 126, 128, 130 and 132, touch sensorpanels 134 and 138, and touch sensors 160 and 162 can be based on mutualcapacitance and/or self-capacitance. The electrodes can be arrange as amatrix of small, individual plates of conductive material (e.g., as intouch node electrodes 408 in touch screen 402 in FIG. 4B) or as drivelines and sense lines (e.g., as in row touch electrodes 404 and columntouch electrodes 406 in touch screen 400 in FIG. 4A), or in anotherpattern. The electrodes can be configurable for mutual capacitance orself-capacitance sensing or a combination of mutual and self-capacitancesensing. For example, in one mode of operation, electrodes can beconfigured to sense mutual capacitance between electrodes and in adifferent mode of operation electrodes can be configured to senseself-capacitance of electrodes. In some examples, some of the electrodescan be configured to sense mutual capacitance therebetween and some ofthe electrodes can be configured to sense self-capacitance thereof.

FIG. 2 illustrates an example computing system including a touch screenthat can use balanced mutual capacitance techniques according toexamples of the disclosure. Computing system 200 can be included in, forexample, a mobile phone, tablet, touchpad, portable or desktop computer,portable media player, wearable device or any mobile or non-mobilecomputing device that includes a touch screen or touch sensor panel.Computing system 200 can include a touch sensing system including one ormore touch processors 202, peripherals 204, a touch controller 206, andtouch sensing circuitry (described in more detail below). Peripherals204 can include, but are not limited to, random access memory (RAM) orother types of memory or storage, watchdog timers, co-processor(s) andthe like. Touch controller 206 can include, but is not limited to, oneor more sense channels 208, channel scan logic 210 and driver logic 214.Channel scan logic 210 can access RAM 212, autonomously read data fromthe sense channels and provide control for the sense channels. Inaddition, channel scan logic 210 can control driver logic 214 togenerate stimulation signals 216 at various frequencies and/or phasesthat can be selectively applied to drive regions of the touch sensingcircuitry of touch screen 220, as described in more detail below. Insome examples, touch controller 206, touch processor 202 and peripherals204 can be integrated into a single application specific integratedcircuit (ASIC), and in some examples can be integrated with touch screen220 itself.

It should be apparent that the architecture shown in FIG. 2 is only oneexample architecture of computing system 200, and that the system couldhave more or fewer components than shown, or a different configurationof components. The various components shown in FIG. 2 can be implementedin hardware, software, firmware or any combination thereof, includingone or more signal processing and/or application specific integratedcircuits.

Computing system 200 can include a host processor 228 for receivingoutputs from touch processor 202 and performing actions based on theoutputs. For example, host processor 228 can be connected to programstorage 232 and a display controller/driver 234 (e.g., a Liquid-CrystalDisplay (LCD) driver). It is understood that although some examples ofthe disclosure may described with reference to LCD displays, the scopeof the disclosure is not so limited and can extend to other types ofdisplays, such as Light-Emitting Diode (LED) displays, including OrganicLED (OLED), Active-Matrix Organic LED (AMOLED) and Passive-MatrixOrganic LED (PMOLED) displays. Display driver 234 can provide voltageson select (e.g., gate) lines to each pixel transistor and can providedata signals along data lines to these same transistors to control thepixel display image.

Host processor 228 can use display driver 234 to generate a displayimage on touch screen 220, such as a display image of a user interface(UI), and can use touch processor 202 and touch controller 206 to detecta touch on or near touch screen 220, such as a touch input to thedisplayed UI. The touch input can be used by computer programs stored inprogram storage 232 to perform actions that can include, but are notlimited to, moving an object such as a cursor or pointer, scrolling orpanning, adjusting control settings, opening a file or document, viewinga menu, making a selection, executing instructions, operating aperipheral device connected to the host device, answering a telephonecall, placing a telephone call, terminating a telephone call, changingthe volume or audio settings, storing information related to telephonecommunications such as addresses, frequently dialed numbers, receivedcalls, missed calls, logging onto a computer or a computer network,permitting authorized individuals access to restricted areas of thecomputer or computer network, loading a user profile associated with auser’s preferred arrangement of the computer desktop, permitting accessto web content, launching a particular program, encrypting or decoding amessage, capturing an image with a camera in communication with theelectronic device, exiting an idle/sleep state of the electronic device,and/or the like. Host processor 228 can also perform additionalfunctions that may not be related to touch processing.

Note that one or more of the functions described herein, including theconfiguration of switches, can be performed by firmware stored in memory(e.g., one of the peripherals 204 in FIG. 2 ) and executed by touchprocessor 202, or stored in program storage 232 and executed by hostprocessor 228. The firmware can also be stored and/or transported withinany non-transitory computer-readable storage medium for use by or inconnection with an instruction execution system, apparatus, or device,such as a computer-based system, processor-containing system, or othersystem that can fetch the instructions from the instruction executionsystem, apparatus, or device and execute the instructions. In thecontext of this document, a “non-transitory computer-readable storagemedium” can be any medium (excluding signals) that can contain or storethe program for use by or in connection with the instruction executionsystem, apparatus, or device. In some examples, RAM 212 or programstorage 232 (or both) can be a non-transitory computer readable storagemedium. One or both of RAM 212 and program storage 232 can have storedtherein instructions, which when executed by touch processor 202 or hostprocessor 228 or both, can cause the device including computing system200 to perform one or more functions and methods of one or more examplesof this disclosure. The computer-readable storage medium can include,but is not limited to, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus or device,a portable computer diskette (magnetic), a random access memory (RAM)(magnetic), a read-only memory (ROM) (magnetic), an erasableprogrammable read-only memory (EPROM) (magnetic), a portable opticaldisc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory suchas compact flash cards, secured digital cards, USB memory devices,memory sticks, and the like.

The firmware can also be propagated within any transport medium for useby or in connection with an instruction execution system, apparatus, ordevice, such as a computer-based system, processor-containing system, orother system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions. Inthe context of this document, a “transport medium” can be any mediumthat can communicate, propagate or transport the program for use by orin connection with the instruction execution system, apparatus, ordevice. The transport medium can include, but is not limited to, anelectronic, magnetic, optical, electromagnetic or infrared wired orwireless propagation medium.

Touch screen 220 can be used to derive touch information at multiplediscrete locations of the touch screen, referred to herein as touchnodes. Touch screen 220 can include touch sensing circuitry that caninclude a capacitive sensing medium having a plurality of drive lines222 and a plurality of sense lines 223. It should be noted that the term“lines” is sometimes used herein to mean simply conductive pathways, asone skilled in the art will readily understand, and is not limited toelements that are strictly linear, but includes pathways that changedirection, and includes pathways of different size, shape, materials,etc. Drive lines 222 can be driven by stimulation signals 216 fromdriver logic 214 through a drive interface 224 and resulting sensesignals 217 generated in sense lines 223 can be transmitted through asense interface 225 to sense channels 208 in touch controller 206. Inthis way, drive lines and sense lines can be part of the touch sensingcircuitry that can interact to form capacitive sensing nodes, which canbe thought of as touch picture elements (touch pixels) and referred toherein as touch nodes, such as touch nodes 226 and 227. This way ofunderstanding can be particularly useful when touch screen 220 is viewedas capturing an “image” of touch (“touch image”). In other words, aftertouch controller 206 has determined whether a touch has been detected ateach touch nodes in the touch screen, the pattern of touch nodes in thetouch screen at which a touch occurred can be thought of as an “image”of touch (e.g., a pattern of fingers touching the touch screen). As usedherein, an electrical component “coupled to” or “connected to” anotherelectrical component encompasses a direct or indirect connectionproviding electrical path for communication or operation between thecoupled components. Thus, for example, drive lines 222 may be directlyconnected to driver logic 214 or indirectly connected to drive logic 214via drive interface 224 and sense lines 223 may be directly connected tosense channels 208 or indirectly connected to sense channels 208 viasense interface 225. In either case an electrical path for drivingand/or sensing the touch nodes can be provided.

FIG. 3A illustrates an exemplary touch sensor circuit corresponding to aself-capacitance measurement of a touch node electrode 302 and sensingcircuit 314 (e.g., corresponding to a sense channel 208) according toexamples of the disclosure. Touch node electrode 302 can correspond to atouch electrode 404 or 406 of touch screen 400 or a touch node electrode408 of touch screen 402. Touch node electrode 302 can have an inherentself-capacitance to ground associated with it, and also an additionalself-capacitance to ground that is formed when an object, such as finger305, is in proximity to or touching the electrode. The totalself-capacitance to ground of touch node electrode 302 can beapproximated as capacitance 304 as capacitance 304 can be much smallerthan the body capacitance 309 and thus can dominate the overall groundcapacitance. Touch node electrode 302 can be coupled to sensing circuit314. Sensing circuit 314 can include an operational amplifier 308,feedback resistor 312 and feedback capacitor 310, although otherconfigurations can be employed. For example, feedback resistor 312 canbe replaced by a switched capacitor resistor in order to minimize aparasitic capacitance effect that can be caused by a variable feedbackresistor. Touch node electrode 302 can be coupled to the inverting input(-) of operational amplifier 308. An AC voltage source 306 (V_(ac)) canbe coupled to the non-inverting input (+) of operational amplifier 308.Touch sensor circuit 300 can be configured to sense changes (e.g.,increases) in the total self-capacitance 304 of the touch node electrode302 induced by a finger or object either touching or in proximity to thetouch sensor panel. The output voltage amplitude of amplifier 308 isapproximately V_(ac)*(1+ X_(FB)/(X_(CS)+X_(CSNS))), where X_(FB), X_(CS)and X_(CSNS) are the impedances of the feedback network, capacitors 307and 304, respectively, at the frequency of V_(ac). The output of theamplifier 308 can be demodulated at the frequency of stimulus signalV_(ac) (homodyne or synchronous detection) by demodulator 328 and thenintegrated (or averaged) by filter 332. The resulting output 320 can beused by a processor to determine the presence of a proximity or touchevent, or the output can be inputted into a discrete logic network todetermine the presence of a proximity or touch event. Note that in someexamples, demodulator can be an I/Q demodulator. In some examples, thedemodulator can be in the digital domain, where the output of amplifier308 could be digitized first by an ADC before performing digitaldemodulation.

FIG. 3B illustrates an exemplary touch sensor circuit 350 correspondingto a mutual-capacitance drive line 322 and sense line 326 and sensingcircuit 314 (e.g., corresponding to a sense channel 208) according toexamples of the disclosure. Drive line 322 can be stimulated bystimulation signal 306 (e.g., an AC voltage signal). Stimulation signal306 can be capacitively coupled to sense line 326 through mutualcapacitance 324 between drive line 322 and the sense line. When a fingeror object 305 approaches the touch node created by the intersection ofdrive line 322 and sense line 326, mutual capacitance 324 can change(e.g., decrease). This change in mutual capacitance 324 can be detectedto indicate a touch or proximity event at the touch node, as describedherein. The sense signal coupled onto sense line 326 can be received bysensing circuit 314. Sensing circuit 314 can include operationalamplifier 308 and at least one of a feedback resistor 312 and a feedbackcapacitor 310. FIG. 3B illustrates a general case in which bothresistive and capacitive feedback elements are utilized. The sensesignal (referred to as V_(in)) can be inputted into the inverting inputof operational amplifier 308, and the non-inverting input of theoperational amplifier can be coupled to a reference voltage V_(ref).Operational amplifier 308 can drive its output to voltage V_(o) to keepV_(in) substantially equal to V_(ref), and can therefore maintain V_(in)constant or virtually grounded. A person of skill in the art wouldunderstand that in this context, equal can include deviations of up to15%. Therefore, the gain of sensing circuit 314 can be mostly a functionof the ratio of mutual capacitance 324 and the feedback impedance,comprised of resistor 312 and/or capacitor 310, and the impedance ofmutual capacitance 324. The output of the amplifier 308 is demodulatedat the frequency of stimulus signal V_(ac) (homodyne or synchronousdetection) by demodulator 328 and then integrated (or averaged) byfilter 332. Note that in some examples, demodulator can be an I/Qdemodulator. In some examples, the demodulator (or I/Q demodulator) canbe in the digital domain, where the output of amplifier 308 can bedigitized first by an ADC before performing demodulation and filtering.

Referring back to FIG. 2 , in some examples, touch screen 220 can be anintegrated touch screen in which touch sensing circuit elements of thetouch sensing system can be integrated into the display pixel stack-upsof a display. The circuit elements in touch screen 220 can include, forexample, elements that can exist in LCD or other displays (LED display,OLED display, etc.), such as one or more pixel transistors (e.g., thinfilm transistors (TFTs)), gate lines, data lines, pixel electrodes andcommon electrodes. In a given display pixel, a voltage between a pixelelectrode and a common electrode can control a luminance of the displaypixel. The voltage on the pixel electrode can be supplied by a data linethrough a pixel transistor, which can be controlled by a gate line. Itis noted that circuit elements are not limited to whole circuitcomponents, such as a whole capacitor, a whole transistor, etc., but caninclude portions of circuitry, such as only one of the two plates of aparallel plate capacitor.

FIG. 4A illustrates touch screen 400 with touch electrodes 404 and 406arranged in rows and columns according to examples of the disclosure.Specifically, touch screen 400 can include a plurality of touchelectrodes 404 disposed as rows, and a plurality of touch electrodes 406disposed as columns. Touch electrodes 404 and touch electrodes 406 canbe on the same or different material layers on touch screen 400, and canintersect with each other, as illustrated in FIG. 4A. In some examples,the electrodes can be formed on opposite sides of a transparent(partially or fully) substrate and from a transparent (partially orfully) semiconductor material, such as ITO, though other materials arepossible. Electrodes displayed on layers on different sides of thesubstrate can be referred to herein as a double-sided sensor. In someexamples, touch screen 400 can sense the self-capacitance of touchelectrodes 404 and 406 to detect touch and/or proximity activity ontouch screen 400, and in some examples, touch screen 400 can sense themutual capacitance between touch electrodes 404 and 406 to detect touchand/or proximity activity on touch screen 400. Although the touchelectrodes 404 and 406 are illustrated as being rectangle-shaped, itshould be understood that other electrode shapes and structures (e.g.,diamond-, square-, stripe- or circle-shaped electrodes connected byjumpers or vias) are possible.

FIG. 4B illustrates touch screen 402 with touch node electrodes 408arranged in a pixelated touch node electrode configuration according toexamples of the disclosure. Specifically, touch screen 402 can include aplurality of individual touch node electrodes 408, each touch nodeelectrode identifying or representing a unique location on the touchscreen at which touch or proximity (i.e., a touch or proximity event) isto be sensed, and each touch node electrode being electrically isolatedfrom the other touch node electrodes in the touch screen/panel, aspreviously described. Touch node electrodes 408 can be on the same ordifferent material layers on touch screen 402. In some examples, touchscreen 402 can sense the self-capacitance of touch node electrodes 408to detect touch and/or proximity activity on touch screen 402, and insome examples, touch screen 402 can sense the mutual capacitance betweentouch node electrodes 408 to detect touch and/or proximity activity ontouch screen 402. Although touch node electrodes 408 are illustrated ashaving rectangular shapes, it should be understood that other electrodeshapes (e.g., diamonds, circles, stripes etc.) and structures arepossible.

FIGS. 5A-5C illustrate exemplary circuit diagrams modeling mutualcapacitance touch sensing in various scenarios according to someexamples of the disclosure. The circuits illustrated in FIGS. 5A-5C canbe illustrated as having one or more Tx electrodes (e.g., driveelectrodes) and one Rx electrode, for example. It should be understoodthat, in some examples, a touch screen can include a plurality of touchnodes and each of the touch nodes can be represented by one of thecircuits illustrated in FIGS. 5A-5C.

For example, the circuit 500 illustrated in FIG. 5A represents mutualcapacitance sensing of a proximate object that is well-grounded. In someexamples, an object is well-grounded if it provides a path to systemground or some other known reference voltage with less than a thresholdimpedance such that the object is effectively grounded. Circuit 500illustrated in FIG. 5A can include Tx electrode 502 (e.g., a driveelectrode), Rx electrode 504 (e.g., a sense electrode), a proximateobject 506 (e.g., a finger of the user, a stylus, or another conductiveobject), and the capacitances between each of the elements of thecircuit 500. Tx electrode 502 can be similar to drive electrode 322described above with reference to FIG. 3B and Rx electrode 504 can besimilar to sense electrode 326 described above with reference to FIG.3B. Note that the system ground connections shown in FIG. 3B can bereferenced to the same ground as earth ground shown in FIGS. 5A-5C.Moreover, circuit 500 can include additional elements not illustrated inFIG. 5A, such as one or more components illustrated in FIG. 3B.

In some examples, when object 506 is proximate to or touching the touchscreen in a scenario modeled by circuit 500, a capacitance C_(1,P) isformed between the object 506 and the Tx electrode 502 and capacitanceC_(2,P) is formed between the object 506 and the Rx electrode 504. Asdescribed above with reference to FIG. 3B, the capacitive coupling ofthe object 506 and the electrodes 502 and 504 can cause the mutualcapacitance C_(1,2) between the Tx electrode 502 and the Rx electrode504 to decrease relative to the mutual capacitance C_(1,2) without theproximity of the object 506. This change in mutual capacitance can besensed as described above, such as with reference to FIG. 3B and theamount of change in the charge into the RX node is ΔQ_(1,2) =V_(Tx)ΔC_(1,2).

In some examples, the mutual capacitance C_(1,2) between the Txelectrode 502 and the Rx electrode 504 decreases in the presence ofobject 506 because the object 506 is well-grounded as described above.As described below with reference to FIGS. 5B-5C, if the object 506 ispoorly grounded, the mutual capacitance C_(1,2) may not decrease inresponse to object 506 to the same extent as C_(1,2) decreases inresponse to a well-grounded object 506. In some examples, an object ispoorly-grounded if it does not provide a path to system ground or someother reference voltage with an impedance below a predeterminedthreshold, such as an object that provides a path to system ground orthe reference voltage with an impedance above the threshold or an objectthat is not coupled to ground or the reference voltage at all. In someexamples, if object 506 is poorly grounded, charge injected throughC_(1,p) and C_(2,P) may cause errors in the estimate of the mutualcapacitance C_(1,2), which may make it appear as though C_(1,2)decreases more, less, not at all, or even increase when the poorlygrounded object 506 is proximate to the touch screen relative to theapparent change in mutual capacitance C_(1,2) when a well-groundedobject is proximate to the touch screen. These variations can cause theelectronic device to fail to detect the object 506 (e.g., because thechange in capacitive coupling is less than a detection threshold), failto detect other objects proximate to the touch screen, or to undergo a“negative pixel effect” in which charge coupled to the object 506 causesthe mutual capacitance C_(1,2) to increase in the presence of the poorlygrounded object instead of decreasing, for example.

FIG. 5B illustrates a circuit 520 representing mutual capacitance touchdetection of a poorly grounded object 506, for example. Circuit 520includes the same Tx electrode 502 and Rx electrode 504 described abovewith reference to FIG. 5A and, like circuit 500 illustrated in FIG. 5A,may include additional elements not illustrated in FIG. 5B, such as oneor more of the elements described above with reference to FIG. 3B.

Unlike circuit 500, the object 506 that is proximate to or in contactwith the touch screen including the Tx electrode 502 and the Rxelectrode 504 can be poorly grounded. As shown in FIG. 5B, the object506 can be capacitively coupled to ground by some capacitance C_(p,gnd)(a capacitive coupling path with greater than the threshold impedance).In essence, C_(1,P) forms a voltage divider with C_(2,P) and unknowncapacitor C_(P,GND) applied to V_(TX) causing a voltage V_(P) to appearat node V_(P). Therefore, the effective charge coupled to the RX node isΔQ_(1,2) = V_(TX)ΔC_(1,2) + V_(P)C₂,_(P). Thus, in some examples, thevoltage V_(P) (which is responsible for the negative pixel term) of theobject 506 can be a different potential than the ground potential.

When sensing touch signals to determine mutual capacitance C_(1,2)between the Tx electrode 502 and the Rx electrode 504 in FIG. 5B, thepoor grounding of object 506 can interfere with the accuracy of thedetermination of C_(1,2) from the measured sense signal. In someexamples, these errors can cause the sensed touch signals to appear asthough there is no object 506 proximate to the touch screen, can cause“negative pixels” to be detected in the touch data or can cause othertouch sensing errors. In some examples, it can be advantageous tomitigate poor grounding to reduce the “negative pixel” effect and othertouch sensing errors.

FIG. 5C illustrates another circuit 540 that can represent mutualcapacitance sensing of a poorly grounded object 506 using multiple drivesignals. Like circuits 500 and 520, circuit 540 can include Rx electrode504 that can be used to sense a proximate object 506 that is close to ortouching the touch screen that includes Rx electrode 504, for example.In some examples, circuit 540 includes two drive electrodes, -Tx 508 band +Tx 508 a, which can be included in the touch screen that includesRx electrode 504. In some examples, the touch screen that includeselectrodes 504, 508 a, and 508 b can further include one or morecomponents described above with reference to FIG. 3B.

In some examples, the +Tx electrode 508 a and the -Tx electrode 508 bcan be driven with balanced drive signals having opposite drivewaveforms. For example, the drive signals can have the same magnitudeand frequency and can be out of phase from each other by 180°. In someexamples, these signals can be capacitively coupled to the proximateobject 506 via capacitances C_(3,p) and C_(1,p). The capacitancesC_(3,p) and C_(1,p) can be the same or substantially the same, forexample. Thus, in some examples, the proximate object 506 can experiencea net voltage of zero from the balanced drive signals (e.g., Vp=0),thereby mitigating the poor grounding of the object 506. For example, ifcharge is being coupled to the surface of the touch screen by way ofobject 506, the charge can have a path to system ground through C_(3,p)and/or C_(1,p). The effective charge coupled into the RX node isΔQ_(1,2) = V_(TX+)ΔC_(1,2) + V_(Tx-)AC_(1,3) = V_(TX)(ΔC_(1,2) -ΔC_(1,3) ).

As shown in FIG. 5C, in some examples, each drive electrode (e.g., +Txelectrode 508 a and -Tx electrode 508 b) can capacitively couple to theRx electrode 504. For example, mutual capacitance C_(1,2) can formbetween the +Tx electrode 508 a and the Rx electrode 504, and mutualcapacitance C_(1,3) can form between the -Tx electrode 508 b and the Rxelectrode 504 . In some examples, the drive voltages applied to eachdrive electrode 508 a and 508 b can capacitively couple to the Rxelectrode 504. In some examples, as shown in FIG. 5C, the -Tx electrode508 b and the +Tx electrode 508 a can each be located a differentdistance from the Rx electrode 504, such that C_(1,2) and C_(1,3) maynot be the same. For example, as shown in FIG. 5C, because the distancebetween +Tx electrode 508 a and Rx electrode 504 is less than thedistance between the -Tx electrode 508 b and the Rx electrode 504,C_(1,2) can be greater than C_(1,3). As a result, the net drive voltagesignal coupled to the Rx electrode 504 can be non-zero and can have thesame phase as the drive signal applied to the +Tx electrode 508 a, forexample. It should be understood that, in some examples, the distancebetween the -Tx electrode 508 b and the Rx electrode 504 can instead beless than the distance between +Tx electrode 508 a and Rx electrode 504.In some examples, positioning the +Tx electrode 508 a and the -Txelectrode 508 b at different distances from the Rx electrode 504 cancause the signal detected at the Rx electrode 504 to be non-zero,thereby enabling detection of a proximate object 506 (e.g., an objectproximate to or touching the touch screen including electrodes 504 and508 a-b) without a resulting net zero mutual capacitance even though thenet voltage coupled to the object 506 from the Tx electrodes 508 a-b canbe zero.

In some examples, circuit 540 can correspond to various electrodelayouts in which the +Tx electrodes 508 a and the -Tx electrodes 508 bhave the same area and different distances from the Rx electrodes 504.Accordingly, various electrode layouts can be implemented according tothe touch sensing needs of a respective electronic device that usesbalanced mutual capacitance touch sensing according to the disclosure.For example, tradeoffs between accuracy, time/power efficiency, touchscreen thickness, and complexity and/or number of routing traces can bemade according to the typical use cases and cost considerations of theelectronic device to select the appropriate electrode layout. Variousexample electrode layouts corresponding to circuit 540 are described inmore detail below with reference to FIGS. 6A-6C and 7 .

FIGS. 6A-6C illustrate exemplary electrode layouts of touch screensaccording to examples of the disclosure. In some examples, the touchscreens can include a plurality of sense electrodes, a plurality ofdrive electrodes driven with voltage signals having a first phase, and aplurality of drive electrodes driven with voltage signals having asecond phase. Each touch node of the touch screens illustrated in FIGS.6A-6C can include a sense electrode, a drive electrode that can bedriven with a voltage signal having a first phase, and a drive electrodethat can be driven with a voltage signal having a second phase, forexample. In some examples, each of these touch nodes can be modeled bycircuit 540 described above with reference to FIG. 5C.

As an example, the touch screen 600 in FIG. 6A can include a pluralityof Rx electrodes 604 (e.g., sense electrodes), a plurality of +Txelectrodes 608 a (e.g., drive electrodes that can be driven with avoltage signal having a first phase), and a plurality of -Tx electrodes608 b (e.g., drive electrodes that can be driven with a voltage signalhaving a second phase opposite the first phase). In some examples, theRx electrodes 604 illustrated in FIG. 6A can be modeled by Rx electrode504 illustrated in FIG. 5C, the +Tx electrodes 608 a illustrated in FIG.6A can be modeled by +Tx electrode 508 a illustrated in FIG. 5C, and the-Tx electrodes 608 b illustrated in FIG. 6A can be modeled by the -Txelectrode 508 b illustrated in FIG. 5C. For example, the +Tx electrodes608 a can be driven with drive voltage signals that are out of phasewith the drive voltage signals applied to the -Tx electrodes 608 b by180° (e.g., driving +Tx electrodes 608 a and -Tx electrodes 608 b withbalanced drive signals).

In some examples, as shown in FIG. 6A, the Rx electrodes 604, +Txelectrodes 608 a, and -Tx electrodes 608 b can be arrangedconcentrically. For example, the +Tx electrode 608 a can be disk-shapedincluding a hole in which the circle-shaped Rx electrode 604 can belocated, and the -Tx electrode 608 b can be disk-shaped including a holein which the +Tx electrode 608 a and the Rx electrode 604 can belocated. Although the electrodes 604 and 608 a-b can be circular inshape as shown in FIG. 6A, in some examples, other shapes can be used,such as squares, rectangles, diamonds, triangles, hexagons. In someexamples, a single Rx electrode 604, a single +Tx electrode 608 a, and asingle -Tx electrode 608 b can be associated with a respective touchnode of the touch screen 600. For example, as shown in FIG. 6A, touchscreen 600 can include a touch node at the location of each group ofelectrodes including a respective Rx electrode 604, a respective +Txelectrode 608 a, and a respective -Tx electrode 608 b. In some examples,a plurality Rx electrodes 604, +Tx electrodes 608 a, and -Tx electrodes608 b can be included in each touch node, as described in more detailbelow with reference to FIG. 6B.

Still referring to FIG. 6A, in some examples, the area of the +Txelectrodes 608 a can be equal to (or within a threshold of equal to) thearea of the -Tx electrodes 608 b so that the capacitive coupling of aproximate object to each of the +Tx electrodes 608 a and -Tx electrodes608 b can be equal (or within a threshold of equal). In some examples,making the capacitive coupling to proximate objects of each of the +Txelectrodes 608 a and the -Tx electrodes 608 b equal or substantiallyequal can cause the net voltage experienced by the proximate object tobe zero when the amplitudes and frequencies of the drive signals appliedto the +Tx electrodes 608 a and the -Tx electrodes 608 b are the sameand the phases are opposite (e.g., out of phase by 180°). In someexamples, the area of the Rx electrodes 604 can be the same as ordifferent from the areas of the +Tx electrodes 608 a and the -Txelectrodes 608 b.

As described above with reference to FIG. 5C and as shown in FIG. 6A, insome examples, for each touch node included in touch screen 600, thedistance between the respective +Tx electrode 608 a and the Rx electrode604 can be less than the distance between the respective -Tx electrode608 b and the Rx electrode 604. In some examples, this arrangementcauses the capacitive coupling between the +Tx electrodes 608 a and theRx electrodes 604 to be greater than the capacitive coupling between the-Tx electrodes 608 b and the Rx electrodes 604. Thus, for example, thenet signal sensed by the Rx electrodes 604 can have a non-zero magnitudeand can have the same phase as the drive signal applied to the +Txelectrode 608 a.

As another example, the touch screen 620 in FIG. 6B can include aplurality of touch nodes 622. In some examples, each touch node 622 caninclude an array of electrodes. FIG. 6B illustrates an expanded view ofone such touch node 622 including Rx electrodes 624, +Tx electrodes 628a, -Tx electrodes 628 b, and additional electrodes 626 (e.g., electrodesat a fixed potential or ground during a balanced mutual capacitancetouch scan). In some examples, electrodes 624, 626, and 628 a-b can bemulti-functioning electrodes that can be used as touch electrodes duringa touch phase of touch screen operation and can be used as part ofdisplay circuitry (e.g., as common electrodes, anodes, or cathodesdriven with a ground or reference voltage, a negative voltage, apositive voltage, a data voltage, or other voltage) during a displayphase of touch screen operation. For example, the operation of theelectrodes 624, 626, and 628 a-b can be time multiplexed between displayoperation and touch detection. In some examples, voltages applied toelectrodes 624, 626, and 628 a-b during the display phase can bedifferent from the voltages applied to the +Tx electrodes 628 a and the-Tx electrodes 628 b during the touch detection phase. Exemplaryoperation of the Rx electrodes 624, +Tx electrodes 628 a, and -Txelectrodes 628 b during the touch detection phase will now be described.

In some examples, the Rx electrodes 624 illustrated in FIG. 6B can bemodeled by Rx electrode 504 illustrated in FIG. 5C, the +Tx electrodes628 a illustrated in FIG. 6B can be modeled by +Tx electrode 508 aillustrated in FIG. 5C, and the -Tx electrodes 628 b illustrated in FIG.6B can be modeled by the -Tx electrode 508 b illustrated in FIG. 5C. Forexample, the +Tx electrodes 628 a can be driven with drive voltagesignals that are out of phase with the drive voltage signals applied tothe -Tx electrodes 628 b by 180°.

In some examples, as shown in FIG. 6B, the Rx electrodes 624, +Txelectrodes 628 a, and -Tx electrodes 628 b can be arranged such that thedistance between the +Tx electrodes 628 a and the Rx electrodes 624 canbe less than the distance between the -Tx electrodes 628 b and the Rxelectrodes 624. Thus, in some examples, the capacitive coupling of the+Tx electrodes 628 a to the Rx electrodes 624 can be greater than thecapacitive coupling of the -Tx electrodes 628 b to the Rx electrodes624, and the signal sensed at the Rx electrodes 624 can be non-zero.

In some examples, each touch node 622 can include a plurality of Rxelectrodes 624, a plurality of +Tx electrodes 624 a, and a plurality of-Tx electrodes 624 b. Electrodes of the same type of electrode within arespective touch node 622 may either be electrically isolated or may becoupled together while the touch screen 620 operates in the touchdetection mode, for example. For example, all of the +Tx electrodes 628a within a respective touch node 622 can be independently driven with afirst drive signal simultaneously, all of the -Tx electrodes 628 bwithin the respective touch node 622 can be independently driven with asecond drive signal simultaneously, and each Rx electrode 624 in therespective touch node 622 can be independently sensed. In some examples,the sensed signals for each Rx electrode 624 can be combined orcompared, such as by calculating a mean, median, or mode of the touchsignals to detect touch. As another example, all of the +Tx electrodes628 a in a respective touch node 622 can be coupled together and drivenwith a first drive signal, all of the-Tx electrodes 628 b in therespective touch node 622 can be coupled together and driven with asecond drive signal, and/or all of the Rx electrodes 624 in therespective touch node 622 can be coupled together and sensed during thetouch detection mode. In some examples, some electrodes in a respectivetouch node 622 are coupled together and others remain electricallyisolated. For example, all of the Rx electrodes 624 in a respectivetouch node 622 can be coupled together during the touch detection mode,whereas the +Tx electrodes 628 a and the -Tx electrodes 628 b in therespective touch node 622 can be independently driven with the first andsecond drive signals, respectively. As another example, during the touchdetection mode, all of the +Tx electrodes 628 a of a respective touchnode 622 can be coupled together and driven with a first drive signal,all of the -Tx electrodes 628 b of the respective touch node 622 can becoupled together and driven with a second drive signal, and the Rxelectrodes 624 in the respective touch node 622 can be independentlysensed as previously described.

Still referring to FIG. 6B, in some examples, the total area of the +Txelectrodes 628 a included in a respective touch node 622 can be equal to(or within a threshold of being equal to) the total area of the -Txelectrodes 628 b in the respective touch node 622 so that the capacitivecoupling of a proximate object to each of the +Tx electrodes 628 a and-Tx electrodes 628 b can be equal. In some examples, making thecapacitive coupling to proximate objects of each of the +Tx electrodes628 a and the -Tx electrodes 628 b equal (or nearly equal) can cause thenet voltage applied to the proximate object to be zero (or near zero)when the amplitudes and frequencies of the drive signals applied to the+Tx electrodes 628 a in a respective touch node 622 and the -Txelectrodes 628 b in the respective touch node 622 are the same and thephases are opposite (e.g., out of phase by 180°). In some examples, thetotal area of the Rx electrodes 624 can be the same as or different fromthe total areas of the +Tx electrodes 628 a and the -Tx electrodes 628b.

In some examples, the touch screen 620 can include additional electrodes626. The additional electrodes 626 can be “off” (neither driven with anAC stimulation voltage nor sensed) during the touch detection mode ofthe touch screen 620, in some examples. In some examples, the additionalelectrodes 626 can be coupled to a common voltage (e.g., ground orvirtual ground) or may be floating during the touch detection mode ofthe touch screen 620. In some examples, one or more of the additionalelectrodes 626 can be used as Rx electrodes 626 during the touchdetection mode of the touch screen 620. In some examples, during thedisplay mode, all of the electrodes, including the additional electrodes626, Rx electrodes 624, +Tx electrodes 628 a, and -Tx electrodes 628 bcan be used to display an image on touch screen 620 (e.g., acting as aVcom layer).

In some examples with intersecting drive electrodes and sense electrodes(e.g., in a row/column arrangement) similar to the touch screen 400illustrated in FIG. 4A, the touch electrodes can each be included inmultiple touch nodes and each touch node can include an Rx electrode, a+Tx electrode, and a -Tx electrode, as will now be described withreference to FIG. 6C. As shown in FIG. 6C,, in some examples, a touchscreen 640 can include Rx electrodes 644 arranged in rows and +Txelectrodes 648 a and -Tx electrodes 648 b arranged in columns. It shouldbe understood that, in some examples, the Rx electrodes 644 can bearranged in rows and the Tx electrodes 628 a and 628 b can be arrangedin columns. The touch nodes of touch screen 640 can be defined asintersections of a row of Rx electrodes 644 with a column of +Txelectrodes 648 a and -Tx electrodes 648 b. As shown in FIG. 6C, thesegments of the touch electrodes can be diamond shape but it should beunderstood that, in some examples, other shapes are possible, such assquares, circles, triangles, hexagons, pentagons, etc.

In some examples, the Rx electrodes 644 illustrated in FIG. 6C can bemodeled by Rx electrode 504 illustrated in FIG. 5C, the +Tx electrodes648 a illustrated in FIG. 6C can be modeled by +Tx electrode 508 aillustrated in FIG. 5C, and the -Tx electrodes 648 b illustrated in FIG.6C can be modeled by the -Tx electrode 508 b illustrated in FIG. 5C. Forexample, the +Tx electrode 648 a corresponding to a respective columncan be driven with drive voltage signals that are out of phase with thedrive voltage signals applied to the -Tx electrode 648 b correspondingto the same respective column by 180°. In some examples, the +Txelectrode 648 a in a respective column can include diamond-shapedsegments (including diamond-shaped holes in which segments of the -Txelectrodes 648 b can be disposed) connected together by jumpers, traces,vias, or other suitable conductive connectors and the -Tx electrodes 648b in a respective column can include diamond-shaped segments connectedtogether by jumpers traces, vias, or other suitable conductiveconnectors. The +Tx electrodes 648 a are not electrically coupled to the-Tx electrodes 648 b.

In some examples, as shown in FIG. 6C, the Rx electrodes 644, +Txelectrodes 648 a, and -Tx electrodes 648 b can be arranged such that thedistance between the +Tx electrodes 648 a and the Rx electrodes 624 isless than the distance between the -Tx electrodes 648 b and the Rxelectrodes 624. For example, each column of Tx electrodes can includediamond-shaped segments of -Tx electrodes 648 b that are surrounded bydiamond-shaped segments of +Tx electrodes 648 a that includediamond-shaped holes in which the segments of the -Tx electrodes 648 bmay be disposed. Thus, in some examples, the capacitive coupling of the+Tx electrodes 648 a to the Rx electrodes 644 can be greater than thecapacitive coupling of the -Tx electrodes 648 b to the Rx electrodes 644and the signal sensed at the Rx electrodes 644 can be non-zero.

In some examples, the area of the +Tx electrodes 648 a can be equal orwithin a predetermined threshold of equal to the area of the -Txelectrodes 648 b so that the capacitive coupling of a proximate objectto each of the +Tx electrodes 648 a and -Tx electrodes 648 b can beequal. In some examples, making the capacitive coupling to proximateobjects of each of the +Tx electrodes 648 a and the -Tx electrodes 648 bequal can cause the net voltage experienced by the proximate object tobe zero when the amplitudes and frequencies of the drive signals appliedto the +Tx electrodes 648 a in a respective column and the -Txelectrodes 648 b in the respective column are the same and the phasesare opposite (e.g., out of phase by 180°). In some examples, the area ofthe Rx electrodes 644 can be the same as or different from the areas ofthe +Tx electrodes 648 a and the -Tx electrodes 648 b.

As described in more detail below with reference to FIG. 8B, in someexamples, touch screens 600, 620, and 640 can perform multiple types oftouch detection scans, including a mutual capacitance scan and aself-capacitance scan. In some examples, during the mutual capacitancescan, the +Tx electrodes can be driven with a first drive signal, the-Tx electrodes can be driven with a second drive signal, and the Rxelectrodes can be sensed as described above, such as with reference toFIG. 3B. In some examples, the first drive signal and second drivesignal applied to a respective touch node have the same frequency andamplitude and opposite phases. In some examples, the drive signalsapplied to different touch nodes can have different phases and/orfrequencies and/or can be applied at different times.

In some examples, during the self-capacitance scan, the self-capacitanceof one or more touch electrodes can be sensed in a manner similar to themanner described above with reference to FIG. 3A. In some examples, thedesignations between the Rx electrodes, +Tx electrodes, and -Txelectrodes may not apply during self-capacitance scanning and, instead,different groups of electrodes can be designated for differences infunctionality or all of the touch electrodes can be used in the same orin similar ways during self-capacitance sensing. For example, theself-capacitance of one or more of the Rx electrodes, +Tx electrodes,and -Tx electrodes can be sensed during the self-capacitance scan. Insome examples, one or more touch electrodes can be coupled togetherduring the self-capacitance scan. For example, all of the touchelectrodes within a respective touch node can be coupled together duringthe self-capacitance scan. As another example, referring to FIG. 6B, allof the electrodes of the same type (e.g., Rx electrodes 624, +Txelectrodes 628 a, or -Tx electrodes 628 b) within a respective touchnode 622 can be coupled together during the self-capacitance scan ordifferent groups of touch electrodes can be coupled together forself-capacitance sensing. In some examples, the self-capacitance of eachelectrode can be sensed separately. In some examples, during theself-capacitance scan all of the electrodes of the touch sensor panelcan be stimulated (and some or all of the electrodes can be sensed tomeasure self-capacitance), such that floating objects, such as water orother liquid, does not provide a conductive path between electrodes (dueto all the electrodes being at the same potential due to the sharedstimulation signal) and, therefore, the floating object may not bedetected.

As described above, in some examples, the balanced mutual capacitancetouch scan described with reference to FIGS. 5C-6C can detectwell-grounded objects and poorly grounded objects that are proximate toor touching a touch screen, touch sensor panel, or touch sensor. In somesituations, it can be advantageous to differentiate betweenwell-grounded objects and floating objects. For example, water or otherliquids present on the surface of a touch screen, touch sensor panel, ortouch sensor can be floating and can be indistinguishable from otherobjects, such as a user’s hands, a stylus, or other conductive objectwhen sensing touch with the balanced mutual capacitance scan (which mayalso be poorly grounded). However, detecting water or liquids asindistinguishable from touches can result in undesired behavior in a wetenvironment. In some examples, a self-capacitance scan may be used todifferentiate between water/liquids and other poorly grounded objects,because a self-capacitance scan may not detect floating water/liquids(and some poorly grounded) objects. Thus, in some examples, the touchdata collected using the balanced mutual capacitance touch scan and thetouch data collected using the self-capacitance scan can be compared toidentify water or other liquids that may appear in balanced mutualcapacitance touch data but may not appear in the self-capacitance touchdata. In some examples, touches in the balanced mutual capacitance touchdata due to water or liquids can be ignored, optionally based on one ormore additional criteria (e.g., size, location, touch thresholds, etc.).In some examples, ignoring touches made by water or liquids can preventthe electronic device from performing one or more unintended actionsthat would otherwise result from detecting water or liquid on thesurface of the touch screen as a touch by an object such as a finger.

FIG. 7 illustrates a side view of an exemplary touch sensor 700according to some examples of the disclosure. In some examples, thetouch sensor 700 can be a touch screen, touch sensor panel, or touchsensor incorporated into one of the devices described above with respectto FIGS. 1A-1H. In some examples, a touch screen or touch sensor panelcan include multiple touch nodes similar to the touch node of touchsensor 700 illustrated in FIG. 7 . In some examples, a touch sensor caninclude one touch node similar to the touch node of touch sensor 700illustrated in FIG. 7 .

As an example, the touch sensor 700 in FIG. 7 can include an Rxelectrode 704 (e.g., sense electrode), a +Tx electrode 708 a (e.g.,drive electrode driven with a first phase), and a -Tx electrode 708 b(e.g., drive electrode driven with a second phase opposite the firstphase). In some examples, the Rx electrode 704 illustrated in FIG. 7 canbe modeled by Rx electrode 504 illustrated in FIG. 5C, the +Tx electrode708 a illustrated in FIG. 7 can be modeled by +Tx electrode 508 aillustrated in FIG. 5C, and the -Tx electrode 708 b illustrated in FIG.7 can be modeled by the -Tx electrode 508 b illustrated in FIG. 5C. Forexample, the +Tx electrode 708 a can be driven with a drive voltagesignal that is out of phase with the drive voltage signal applied to the-Tx electrode 708 b by 180°.

As previously mentioned, FIG. 7 can illustrate an exemplary side view ofa touch sensor 700. In some examples, the electrodes 704 and 708 a-b canbe arranged in a variety of possible top-view orientations correspondingto the side view illustrated in FIG. 7 . For example, a number ofelectrode sizes, shapes, or arrangements can be used. As shown in FIG. 7, in some examples, the +Tx electrode 708 a is located between the Rxelectrode 704 and the -Tx electrode 708 b. Thus, for example, thedistance between the +Tx electrode 708 a and the Rx electrode 704 can beless than the distance between the -Tx electrode 708 b and the Rxelectrode 704. In some examples, this arrangement causes the capacitivecoupling between the +Tx electrode 708 a and the Rx electrode 704 to begreater than the capacitive coupling between the -Tx electrode 708 b andthe Rx electrode 704. Thus, for example, the net signal sensed by the Rxelectrode 704 can have a non-zero magnitude and can have the same phaseas the drive signal applied to the +Tx electrode 708 a.

In some examples, the area of the +Tx electrode 708 a (e.g., in a topview, not shown) can be equal or within a threshold of equal to the areaof the -Tx electrode 708 b (e.g., in a top view, not shown) so that thecapacitive coupling of a proximate object to each of the +Tx electrode708 a and -Tx electrode 708 b can be equal. In some examples, making thecapacitive coupling to proximate objects of each of the +Tx electrode708 a and the -Tx electrode 708 b equal can cause the net voltageapplied to the proximate object to be zero when the amplitudes andfrequencies of the drive signals experienced by the +Tx electrode 708 aand the -Tx electrode 708 b are the same and the phases are opposite(e.g., out of phase by 180°). In some examples, applying a net voltageof zero to the proximate object can prevent the negative pixel effectand other touch detection errors associated with poor grounding fromoccurring. In some examples, the area of the Rx electrode 704 (e.g.,from a top view, not shown) can be the same as or different from theareas of the +Tx electrode 708 a and the -Tx electrode 708 b.

In some examples, the Rx electrode 704, +Tx electrode 708 a, and -Txelectrode 708 b can be disposed on a substrate 712. The touch sensor 700can further include an outer surface 710 that is separated from thesubstrate by gap 714, for example. In some examples, when a proximateobject touches the outside of outer surface 710, the outer surface 710is able to deflect, which can reduce the gap 714 between the outersurface 710 and the substrate 712. When the gap 714 reduces, in someexamples, the proximate object is able to move closer to the electrodes704 and 708 a-b than would be possible if the outer surface 710 did notdeflect. Thus, in some examples, the deflection of the outer surface 710can increase the capacitive coupling of the proximate object to theelectrodes 704 and 708 a-b, and by measuring changes in the mutualcapacitance, a touch can be detected and/or an amount of force can beinferred from the change in the gap 714. Thus, the increase incapacitive coupling can improve the accuracy of the touch sensor700and/or provide force-sensing capability to the touch sensor.

In some examples, substrate 712 can be included in a system-in-package(SIP) including one or more sensors (including or excluding the touchsensor) integrated as a chip. Thus, in some examples, electrodes 704 and708 a-b can be included in the SIP. In some examples, the electrodes 704and 708 a-b can be external to the SIP.

FIGS. 8A-8B are flow charts illustrating exemplary processes 800 and 810including balanced mutual capacitance touch sensing according to someexamples. In some examples, processes 800 and 810 can be performed byone or more touchscreens, touch sensor panels, or touch sensorsdescribed above with reference to FIGS. 1A-7 .

Referring to FIG. 8A, in some examples, process 800 can be used toperform balanced mutual capacitance touch sensing. Although process 800is described below as being performed by an electronic device includinga touch screen (e.g., 600, 620, and/or 640), it should be understoodthat, in some examples, a touch sensor (e.g., touch sensor 700) or touchsensor panel can be used to perform process 800.

In some examples, the electronic device applies (802) drive signals tothe Tx electrodes of the touch screen. For example, a first drivevoltage signal can be applied to one or more +Tx electrodes of the touchscreen and a second drive voltage signal can be applied to one or more-Tx electrodes of the touch screen. In some examples, the first andsecond drive voltage signals can have the same amplitude and frequency.In some examples, the first and second drive voltage signals can haveopposite phases (e.g., the first and second drive voltage signals can beout of phase with one another by 180°).

In some examples, the electronic device senses (804) touch signals atthe Rx electrodes of the touch screen. In some examples, sensing thetouch signals can allow the electronic device to determine the change inmutual capacitance between the Rx electrodes and the -Tx electrodes andbetween the Rx electrodes and the +Tx electrodes. Although, in someexamples, as described above, the drive voltage signals applied to the+Tx electrodes and the -Tx electrodes can have a combined voltage ofzero or substantially zero, because the +Tx electrodes and the -Txelectrodes are different distances from the Rx electrodes, the net drivesignal coupled to the Rx electrodes can be non-zero. Thus, for example,the electronic device is able to sense a change in the signal coupled tothe Rx electrodes to detect touch.

In some examples, the electronic device processes (806) the detectedtouch(es) and, in some examples, detected force at the surface of thetouch screen. Detecting touches at the surface of the touch screenoptionally includes detecting objects proximate to, but not touching,the surface of the touch screen. For example, one or more objectshovering proximate to the surface of the touch screen can be detected.In some examples, processing touch can include identifying one or morecontact areas or hover areas of the touch screen that overlap withlocations at which objects are touching and/or hovering. In someexamples, processing touch can include tracking the movement of one ormore proximate objects, such as to detect swipes or other gestures thatinclude movement of a proximate object. The electronic device is able toperform one or more actions in response to the processed touch, such asnavigating one or more user interfaces of the electronic device, makingselections, for example, and the like.

As described above, in some examples, an electronic device performsmultiple types of touch scans to distinguish well-grounded objects andpoorly grounded objects proximate to or touching the surface of a touchscreen, touch sensor, or touch sensor panel according to process 810,which will now be described with reference to FIG. 8B.

In some examples, an electronic device can perform 812 a first mutualcapacitance touch sensing process (e.g., a balanced mutual capacitancetouch sensing process) using the touch screen. The balanced mutualcapacitance touch sensing process can include one or more steps ofprocess 800 described above with reference to FIG. 8A, for example. Insome examples, the balanced mutual capacitance touch sensing process caninclude applying first drive voltage signals to one or more +Txelectrodes of the touch screen and applying second drive voltage signalsto one or more -Tx electrodes of the touch screen. For example, thefirst drive voltage signal and the second drive voltage signal can havethe same amplitude and frequency and can have opposite phases (e.g., thefirst and second drive voltage signals can be out of phase with oneanother by 180°). The balanced mutual capacitance touch sensing processcan further include sensing the capacitively coupled signal at the Rxelectrodes to determine the change in mutual capacitance between the Rxelectrodes and the +Tx and -Tx electrodes to detect proximate objects.In some examples, the balanced mutual capacitance touch sensing processcan be used to detect well-grounded and poorly grounded objectsproximate to the touch screen.

In some examples, the electronic device can perform 813 a second mutualcapacitance touch sensing process using the touch screen. In someexamples, during the second mutual capacitance touch sensing process,the drive signals applied to the +Tx electrodes and -Tx may not have anet voltage of zero. For example, within a respective touch node, thesame drive signal can be applied to both the +Tx electrode(s) and -Txelectrode(s) of the respective touch node.

In some examples, the electronic device can perform 812 the first mutualcapacitance touch sensing and perform 813 the second mutual capacitancetouch sensing at different times. In some examples, the electronicdevice can perform 812 the first mutual capacitance touch sensing andperform 813 the second mutual capacitance touch sensing concurrently.For example, the electronic device can drive the +Tx electrode(s) of arespective touch node with a drive signal that includes a firstfrequency with a first phase and a second frequency with a third phaseand drive the -Tx electrode(s) of the respective touch node with a drivesignal that includes the first frequency with a second phase, oppositethe first phase, and the second frequency with the third phase. In thisway, in some examples, the components of the touch signals having thefirst phase can be balanced and have a net voltage of zero while thecomponents of the touch signals having the second phase can have anon-zero net voltage. The first and second frequencies can be different.In some examples, the electronic device can demodulate the receivedsense signals at both the first and second frequencies to analyze thetouch data of both the first mutual capacitance and second mutualcapacitance touch sensing processes.

In some examples, the electronic device can perform 814 aself-capacitance touch sensing process using the touch screen. Theself-capacitance touch sensing process can be similar to the descriptionof self-capacitance above with reference to FIG. 3A, for example. Insome examples, one or more of the Rx, +Tx, and/or -Tx electrodes can beused to detect touch using self-capacitance. In some examples, theelectronic device can detect well-grounded objects proximate to thetouch screen using self-capacitance. In some examples, floating water orliquids may not change the self-capacitance enough to be detected duringthe self-capacitance touch sensing process.

In some examples, the electronic device can process (816) the touchdata, which can include processing touch data collected during thebalanced mutual capacitance touch sensing process and touch datacollected during the self-capacitance touch sensing process. In someexamples, processing (816) the touch data in process 810 can include oneor more of the details of the ways the electronic device processes (806)the touch data according to process 800 described above with referenceto FIG. 8A. In some examples, processing (816) touch in process 810 caninclude comparing the touch data collected from the balanced mutualcapacitance touch sensing process 812 and the self-capacitance touchsensing process 814. Comparing the touch data can enable the electronicdevice to differentiate floating water or liquids and from poorlygrounded or well-grounded proximate objects (e.g., fingers, etc.). Insome examples, the electronic device can ignore touches from floatingwater or liquids based on one or more criteria, such as size, shape,location, duration, etc. of the detected touch. In some examples, thecriteria can be selected to avoid processing indications of touch causedby water on the surface of the touch screen that are not based on anintentional user input. Examples of indications of touch based onintentional user input can include users touching the touch screen withtheir hands or fingers, and/or with a stylus or other input device andintentional user input can be detected based on the proximity of otherobjects not expressly recited here.

Some examples of the disclosure relate to an electronic device,comprising: a touch sensor panel including a plurality of first driveelectrodes, a plurality of second drive electrodes, and a plurality ofsense electrodes, wherein each touch node of a plurality of touch nodesincluded in the touch sensor panel includes a first drive electrode, asecond drive electrode, and a sense electrode; and drive circuitryconfigured to, for each touch node: apply a first drive signal to thefirst drive electrode; and apply a second drive signal to the seconddrive electrode, wherein a phase of the first drive signal is oppositefrom a phase of the second drive signal; and sense circuitry configuredto, for each touch node: sense a voltage of the sense electrode, thevoltage indicative of mutual capacitances between the sense electrodeand the first drive electrode and between the sense electrode and thesecond drive electrode.

Some examples of the disclosure are directed to a touch sensor includinga first drive electrode, a second drive electrode, and a senseelectrode; and drive circuitry configured to: apply a first drive signalto the first drive electrode; and apply a second drive signal to thesecond drive electrode, wherein a phase of the first drive signal isdifferent from a phase of the second drive signal; and sense circuitryconfigured to: sense a voltage of the sense electrode, the voltageindicative of mutual capacitances between the sense electrode and thefirst drive electrode and between the sense electrode and the seconddrive electrode. Additionally or alternatively, in some examples, adistance between the first drive electrode and the sense electrode isdifferent from a distance between the second drive electrode and thesense electrode. Additionally or alternatively, in some examples, anarea of the first drive electrode is the same as an area of the seconddrive electrode. Additionally or alternatively, in some examples, anamplitude of the first drive signal is the same as an amplitude of thesecond drive signal, and a frequency of the first drive signal is thesame as a frequency of the second drive signal. Additionally oralternatively, in some examples, a sum of the first drive signal and thesecond drive signal is substantially zero volts. Additionally oralternatively, in some examples, a mutual capacitance of the first driveelectrode and the sense electrode is different from a mutual capacitanceof the second drive electrode and the sense electrode. Additionally oralternatively, in some examples, the touch sensor is one of a pluralityof touch nodes included in a touch sensor panel of the electronicdevice, each touch node included in the touch sensor panel includes arespective sense electrode, a respective first drive electrode, and arespective second drive electrode, the respective sense electrode issurrounded by the respective first drive electrode, and the respectivefirst drive electrode and respective sense electrode are surrounded bythe respective second drive electrode. Additionally or alternatively, insome examples, the touch sensor is included in a touch sensor panel ofthe electronic device, the touch sensor panel including a plurality offirst drive electrodes, a plurality of second drive electrodes, and aplurality of sense electrodes; each sense electrode includes a pluralityof connected sense electrode segments disposed along a first dimensionof the touch sensor panel, each first drive electrode includes aplurality of connected first drive electrode segments, each second driveelectrode includes a plurality of connected second drive electrodesegments, the plurality of connected first drive electrode segments andthe plurality of second drive electrode segments are disposed along asecond dimension of the touch sensor panel that is perpendicular to thefirst dimension, and each respective first drive electrode segment issurrounded by a respective second drive electrode segment. Additionallyor alternatively, in some examples, the touch sensor is one of aplurality of touch nodes included in a touch sensor panel of theelectronic device, the touch sensor panel including a plurality of firstdrive electrodes, a plurality of second drive electrodes, and aplurality of sense electrodes, each touch node of a plurality of touchnodes included in the touch sensor panel includes a first driveelectrode, a second drive electrode, and a sense electrode, the drivecircuitry is further configured to, at a different time from applyingthe first drive signal to the first drive electrode and applying thesecond drive signal to the second drive electrode, for each touch node:apply a third drive signal to one or more of the first drive electrode,the second drive electrode, or the sense electrode, and the sensecircuity is further configured to, at a different time from sensing thevoltage indicative of the mutual capacitance, for each touch node: senseone or more second voltages of the first drive electrode, the seconddrive electrode, or the sense electrode, the one or more second voltagesindicative of a self capacitance of the touch node. Additionally oralternatively, in some examples, the phase of the first drive signal isopposite from the phase of the second drive signal. Additionally oralternatively, in some examples, the touch sensor is one of a pluralityof touch nodes included in a touch screen of the electronic device, andthe electronic device further comprises: display circuitry configuredto, at a time different from a time during which the drive circuitryapplies the first drive signal and the second drive signal and the sensecircuitry senses the voltage of the sense electrode: apply displaysignals to the first drive electrode, the second drive electrode, andthe sense electrode to display an image on the touch screen of theelectronic device. Additionally or alternatively, in some examples, thevoltage of the sense electrode is sensed during concurrent applicationof both the first drive signal to the first drive electrode and thesecond drive signal to the second drive electrode.

Some examples of the disclosure are directed to a method, comprising: atan electronic device including a touch sensor including a first driveelectrode, a second drive electrode, and a sense electrode: applying,via drive circuitry of the electronic device, a first drive signal tothe first drive electrode; applying, via sense circuitry of theelectronic device, a second drive signal to the second drive electrode,wherein a phase of the first drive signal is different from a phase ofthe second drive signal; and sensing, via sense circuitry of theelectronic device, a voltage of the sense electrode, the voltageindicative of mutual capacitances between the sense electrode and thefirst drive electrode and between the sense electrode and the seconddrive electrode. Additionally or alternatively, in some examples, anamplitude of the first drive signal is the same as an amplitude of thesecond drive signal, and a frequency of the first drive signal is thesame as a frequency of the second drive signal. Additionally oralternatively, in some examples, a sum of the first drive signal and thesecond drive signal is substantially zero volts. Additionally oralternatively, in some examples, a mutual capacitance of a first driveelectrode of a respective touch node of the touch sensor panel and asense electrode of the respective touch node of the touch sensor panelis different from a mutual capacitance of a second drive electrode ofthe respective touch node of the touch sensor panel and the senseelectrode of the respective touch node of the touch sensor panel.Additionally or alternatively, in some examples, at a different timefrom applying the first drive signal to the plurality of first driveelectrodes and applying the second drive signal to the plurality ofsecond drive electrodes, for each touch node: applying, via the drivecircuitry, a third drive signal to one or more of the first driveelectrode, the second drive electrode, or the sense electrode, and at adifferent time from sensing the voltages indicative of the mutualcapacitances: sensing, via the sense circuitry, one or more secondvoltages of the one or more of the first drive electrode, the seconddrive electrode, or the sense electrode, the second voltages indicativeof a self capacitance of the touch node. Additionally or alternatively,in some examples, the phase of the first drive signal is opposite fromthe phase of the second drive signal. Additionally or alternatively, insome examples, the touch sensor is one of a plurality of touch nodesincluded in a touch screen of the electronic device, and method furthercomprises: at a time different from a time during which the drivecircuitry applies the first drive signal and the second drive signal andthe sense circuitry senses the voltage of the sense electrode: applying,via display circuitry, display signals to the first drive electrode, thesecond drive electrode, and the sense electrode to display an image onthe touch screen of the electronic device. Additionally oralternatively, in some examples, the voltage of the sense electrode issensed during concurrent application of both the first drive signal tothe first drive electrode and the second drive signal to the seconddrive electrode.

Some examples of the disclosure are directed to a non-transitorycomputer readable medium storing instructions that, when executed by anelectronic device including a touch sensor including a first driveelectrode, a second drive electrode, and a sense electrode, cause theelectronic device to perform a method comprising: applying, via drivecircuitry of the electronic device, a first drive signal to the firstdrive electrode; applying, via sense circuitry of the electronic device,a second drive signal to the second drive electrode, wherein a phase ofthe first drive signal is different from a phase of the second drivesignal; and sensing, via sense circuitry of the electronic device, avoltage of the sense electrode, the voltage indicative of mutualcapacitances between the sense electrode and the first drive electrodeand between the sense electrode and the second drive electrode.

Although the disclosed examples have been fully described with referenceto the accompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the disclosed examples as defined by the appended claims.

1. A touch sensor panel including: one or more drive electrodesconfigured to be coupled to drive circuitry, the drive circuitryconfigured to apply one or more drive signals to the one or more driveelectrodes during touch sensing, and one or more sense electrodessurrounded by the one or more drive electrodes and configured to becoupled to sense circuitry, the sense circuitry configured to sense oneor more voltages of the one or more sense electrodes indicative of oneor more mutual capacitances between the one or more sense electrodes andthe one or more drive electrodes during the touch sensing.
 2. The touchsensor panel of claim 1, further comprising one or more touch nodes,wherein each touch note of the one or more touch nodes includes a driveelectrode of the one or more drive electrodes and a sense electrode ofthe one or more sense electrodes.
 3. The touch sensor panel of claim 1,wherein the one or more drive electrodes include one or more holes inwhich the one or more sense electrodes are located.
 4. The touch sensorpanel of claim 1, further comprising one or more touch nodes, whereineach touch note of the one or more touch nodes includes a plurality ofdrive electrodes and a plurality of sense electrodes.
 5. The touchsensor panel of claim 3, wherein: a plurality of drive electrodesincluded in a first touch node of the one or more touch nodes areconfigured to be electrically isolated and driven independently whilethe drive circuitry applies the one or more drive signals to the one ormore touch electrodes, and a plurality of sense electrodes included inthe first touch node are configured to be electrically isolated andsensed independently while the sense circuitry senses the one or morevoltages.
 6. The touch sensor panel of claim 4, wherein: a plurality ofdrive electrodes included in a first touch node of the one or more touchnodes are configured to be coupled together while the drive circuitryapplies the one or more drive signals to the one or more touchelectrodes, and a plurality of sense electrodes included in the firsttouch node are configured to be coupled together while the sensecircuitry senses the one or more voltages.
 7. The touch sensor panel ofclaim 1, further comprising: one or more second drive electrodesconfigured to be coupled to the drive circuitry, the drive circuitryfurther configured to apply one or more second drive signals to the oneor more second drive electrodes, the one or more second drive signalshaving a different phase from a phase of the one or more drive signals.8. The touch sensor panel of claim 7, further comprising: one or moresecond sense electrodes surrounded by the one or more second driveelectrodes and configured to be coupled to the sense circuitry, thesense circuitry further configured to sense one or more second voltagesof the one or more second sense electrodes indicative of one or moresecond mutual capacitances between the one or more second senseelectrodes and the one or more second drive electrodes during touchsensing.
 9. The touch sensor panel of claim 7, wherein the phase of theone or more drive signals is opposite from a phase of the one or moresecond drive signals.
 10. The touch sensor panel of claim 1, wherein,the one or more drive electrodes and the one or more sense electrodesare configured to be coupled to display circuitry at a time differentfrom a time during which the touch sensing occurs, and the displaycircuitry is configured to apply display signals to the one or moredrive electrodes and the one or more sense electrodes to display animage.
 11. A non-transitory computer readable medium storinginstructions that, when executed by an electronic device including atouch sensor panel including one or more sense electrodes surrounded byone or more drive electrodes, cause the electronic device to perform amethod comprising: applying one or more drive signals to the one or moredrive electrodes during touch sensing using drive circuitry; and sensingone or more voltages of the one or more sense electrodes indicative ofone or more mutual capacitances between the one or more sense electrodesand the one or more drive electrodes during the touch sensing.
 12. Thenon-transitory computer readable medium of claim 11, wherein the touchsensor panel includes one or more touch nodes, each touch node of theone or more touch nodes including a plurality of drive electrodeselectrically isolated from one another and a plurality of senseelectrodes electrically isolated from each other, and the method furthercomprises: independently driving a plurality of drive electrodesincluded in a first touch node of the one or more touch nodes while thedrive circuity applies the one or more drive signals to the one or moretouch electrodes; and independently sensing a plurality of senseelectrodes included in the first touch node while the sense circuitrysenses the one or more voltages.
 13. The non-transitory computerreadable storage medium of claim 11, wherein the touch sensor panelincludes one or more touch nodes, each touch node of the one or moretouch nodes including a plurality of drive electrodes and a plurality ofsense electrodes, and the method further comprises: coupling together aplurality of drive electrodes included in a first touch node of the oneor more touch nodes while the drive circuitry applies the one or moredrive signals to the one or more touch electrodes; and coupling togethera plurality of sense electrodes included in the first touch node whilethe sense circuitry senses the one or more voltages.
 14. Thenon-transitory computer readable storage medium of claim 11, wherein thetouch sensor panel further includes one or more second drive electrodes,and the method further comprises: applying one or more second drivesignals to the one or more second drive electrodes using the drivecircuitry, the one or more second drive signals having a different phasefrom a phase of the one or more drive signals.
 15. The non-transitorycomputer readable storage medium of claim 14, wherein the touch sensorpanel further includes one or more second sense electrodes surrounded bythe one or more second drive electrodes, and the method furthercomprises: sensing one or more second voltages of the one or more secondsense electrodes indicative of one or more second mutual capacitancesbetween the one or more second sense electrodes and the one or moresecond drive electrodes during touch sensing using the sense circuitry.16. The non-transitory computer readable storage medium of claim 14,wherein the phase of the one or more drive signals is opposite from aphase of the one or more second drive signals.
 17. The non-transitorycomputer readable storage medium of claim 11, wherein the method furthercomprises, at a time different from a time during which touch sensingoccurs: coupling the one or more sense electrodes and the one or moredrive electrodes to display circuitry; and applying display signals tothe one or more drive electrodes and the one or more sense electrodes todisplay an image using the display circuitry.
 18. A method performed atan electronic device including a touch sensor panel including one ormore sense electrodes surrounded by one or more drive electrodes, themethod comprising: applying one or more drive signals to the one or moredrive electrodes during touch sensing using drive circuitry; and sensingone or more voltages of the one or more sense electrodes indicative ofone or more mutual capacitances between the one or more sense electrodesand the one or more drive electrodes during the touch sensing.
 19. Themethod of claim 18, wherein the touch sensor panel further includes oneor more second sense electrodes surrounded by the one or more seconddrive electrodes, and the method further comprises: sensing one or moresecond voltages of the one or more second sense electrodes indicative ofone or more second mutual capacitances between the one or more secondsense electrodes and the one or more second drive electrodes duringtouch sensing using the sense circuitry.
 20. The method of claim 18,further comprising, at a time different from a time during which touchsensing occurs: coupling the one or more sense electrodes and the one ormore drive electrodes to display circuitry; and applying display signalsto the one or more drive electrodes and the one or more sense electrodesto display an image using the display circuitry.